Hillary

What do you think?

Just two crowns here. Teeth 7 and 8 as circled.
Basically these teeth look too good, they have no real imperfections and look like teeth on a 25 year old. The crown on tooth 8 (the one more in the center) is the more obvious crown because it's shape is clearly different than the tooth next to it.

This picture shows what is known as metamerism. The crowns look like a significantly different color than her other teeth because of the cameras flash. These teeth would not look that different under more normal lighting conditions.

Biden

Nice looking grill here, not officially announced candidacy yet but he gets thrown in here anyways.

What do you think? Have any of these teeth been worked on?

Answer: These are all crowns. Pretty expensive work here. There are several giveaways.
The uniformity of the color on each tooth is one giveaway. Each teeth should have some color variation, but instead each looks almost completely uniform.
The shapes of the teeth are also a giveaway. The two front teeth are ok. The tooth next to the two front teeth (tooth 7, maxillary right lateral incisor) looks a little funnily shaped, (the crown looks too long). The canine here has a rounded cusp, which is definitely not right. It would either be pointed, or flattened on top. It would not be round like that.

Obama extra here. What do you think?

I got nothin. These teeth all look perfectly natural.

Martin O'Malley

Take a look

Teeth look perfectly natural

Especially notice the shape of the canine

Old Bernie

What do you think?

Teeth 9,10,11 as circled are a bridge. He likely lost tooth 10 at some point for some reason and had the tooth replaced with the bridge. There are a couple big givesways here. First if you look closely you can tell all three teeth are connected. Secondly, the color is slightly off.The color can be off for a couple reasons. One reason is that they just picked the wrong color at the beginning. I think it is more likely that Bernie has bleached his teeth a little since he got the bridge, leaving the bridge the same color as it was before the bleaching.